The chemistry of fallout-debris formation in nuclear fireball environments is controlled by multiple inter-dependent parameters, including the composition and temperature of the fireball. Understanding high-temperature chemistry is important to constraining vapor-phase fractionation, which ultimately controls condensed-phase compositions. In this work, we explore the high-temperature molecular chemistry of uranium and oxygen during plasma condensation for the purposes of constraining fallout formation conditions. To study molecular formation at relevant temperatures (&lt;1 eV), we ablated a uranium metal target in carrier gasses having a range of oxygen concentrations to study the effect of oxygen fugacity on uranium oxide formation in the vapor phase. Ablation experiments were conducted with a pulsed Nd:YAG laser (~7 ns pulse length), and the formation of uranium monoxide (UO) was studied via time-resolved emission spectroscopy. Emission spectra were acquired (with ns-scale gate-widths and delay times) using an intensified CCD (ICCD) and a grating spectrometer. These data will be used to calibrate a computational kinetics model, which is being developed as a predictive tool for molecular formation studies in high-temperature systems by our collaborators at University of Illinois, Urbana-Champaign.<br/>

Uranium chemistry in condensing laser-induced plasmas

2019 Spring National Meeting

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